Electrochemical performance of Li-ion batteries containing biphenyl, vinyl ethylene carbonate in liquid electrolyte

This paper investigated the electrochemical behavior and thermal properties of vinyl ethylene carbonate (VEC) and biphenyl (BP) additives with triphenyl phosphate (TPP)-based, nonflammable electrolytes for Li- ion batteries. Mesocarbon microbeads and LiCoO2 were used as the anode and cathode materials, respectively. The main analysis tools were cyclic voltammetry, differential scanning calorimetry, electrochemical impedance spectroscopy, and scanning electron microscopy. The results showed that the oxidizing potential of VEC and BP is about 4.9 and 4.6 V vs Li/Li+, respectively, in TPP-containing electrolytes. Consequently, we found that the addition of 0.1 wt % BP to TPP-based electrolytes improved the cell performance and thermal stability of electrolytes for Li- ion batteries. (c) 2007 The Electrochemical Society.